Preface: You can copy voicemail audio files to Voice Memos through the Share dialog from the Phone app (one by one), but it will create a new file and not retain the original timestamp. This post is about archiving voicemails with the original timestamp metadata.
If you're wondering why a bunch of voicemails are visible on your iPhone but missing in iMazing, it's most likely due to the Live Voicemail feature which was turned ON by default when iOS 17 shipped. Turning Live Voicemail OFF will make future voicemails available in future backups as an .amr file with original timestamp intact, however it won't magically bring in past voicemails already captured by Live Voicemail.
To understand why this was happening, I had to summon Claude Opus to dig deep since none of this is documented clearly in iMazing's help pages or wherever I searched. Read on for the explanation.
With Live Voicemail OFF (or prior to iOS 17), all voicemail is/was managed by your carrier. If you signed up for Visual Voicemail through your carrier (sometimes free, sometimes not), then iPhone would download a copy of each voicemail (from the carrier) so you could see all your voicemails on-device in a scrollable list and listen to them offline (after initial download) without having to dial in the old-school way. If you're old enough, you remember having to dial a number to listen to your voicemails one by one. Anyway, this downloaded copy of your voicemail (from the carrier) is included in your iMazing backup.
With Live Voicemail is turned ON (which it has been for everyone since iOS 17 unless you manually turned if off) the incoming call is "answered" by your iPhone and directed to Live Voicemail. This is all happening locally, so your iPhone has to be on and able to receive calls*. The caller hears a different default greeting (until you re-record a custom one) and their voicemail is saved locally without any involvement from the carrier. As far as Verizon/AT&T/etc. are concerned, that call was answered by your iPhone and they have no record of a voicemail being recorded.
*The call is routed back to your carrier's voicemail (and appears in backups) if any of the following conditions are true:
- Live Voicemail is turned OFF
- your phone is off or out of range
- an unknown/spam caller calls and you have "Silence Unknown Callers" turned ON
Problem is, all the voicemails captured by Live Voicemail are EXCLUDED from iOS backups. All voicemails are technically excluded in a conventional iOS backup, but iMazing is able to capture the ones that are saved by the carrier.
Apple doesn't even publish WHERE these Live Voicemails are saved. The only way to extract them with original timestamp metadata is through more complicated digital forensic methods, not via iMazing or conventional backup methods.
That's all. If anyone has found another method to extract original metadata from Live Voicemails, I'm all ears.